Methods for producing fuels and solvents

ABSTRACT

Described herein are methods for producing fuels and solvents from fatty acid resources. Also disclosed herein are fuels and solvents produced by the methods described herein.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 11/776,047 filed on Jul. 11, 2007, which claims priority upon U.S.provisional application Ser. No. 60/807,358, filed Jul. 14, 2006. Theapplications are hereby incorporated by reference in their entiretiesfor all of their teachings.

BACKGROUND

There are increasing social and economic pressures to develop renewableenergy sources as well as renewable and biodegradable industrial andconsumer to products and materials. The catalytic conversion of naturalfeedstocks to value-added products has resulted in new approaches andtechnologies whose application spans across the traditional economicsectors. There is a new focus on biorefining, which can be described asthe processing of agricultural and forestry feedstocks capturingincreased value by processing them into multiple products includingplatform chemicals, fuels, and consumer products. The conversion oftallow and other organic oils to biodiesel has been previously studiedin depth. Traditionally, this conversion involves thetrans-esterification of the triglyceride to produce threemethyl-esterified fatty acids and a free glycerol molecule. Thechemical, rheological, and combustion properties of the resulting“biodiesel” have also been extensively investigated. Unfortunately,these methyl-ester based fuels have been shown to be far moresusceptible to oxidation and have lower heating values than thetraditional petroleum based diesel fuels. As a result the traditionalbiodiesels must be blended with existing diesel stock and may also haveto be supplemented with antioxidants to prolong storage life and avoiddeposit formation in tanks, fuel systems, and filters.

If methyl-esterification can be considered a clean controlled reaction,a relatively crude alternative that has been utilized previously inindustry is pyrolysis. Pyrolysis involves the use of a thermal treatmentof an agricultural substrate to produce a liquid fuel product. Mostliterature reports utilize raw unprocessed agricultural commodities toproduce a value-added fuel. Many different approaches to pyrolysis as amechanism of producing a liquid fuel have been reported in theliterature and fall under various regimes including flash, fast, andslow pyrolysis. The pyrolysis of a variety of agricultural productsunder these different regimes has been previously investigated,including castor oil, pine wood, sweet sorghum, and canola. Depending onthe conditions used including the temperature used, residence time, andpurity of substrate the balance of products produced varies betweenvapors, liquids, and residual solids (char).

One of the few studies to look at the pyrolysis of fatty acids insteadof the triglycerides or more complex substrates focused on the pyrolysisof the salt of the fatty acid. The conditions used in the study weresuch that a homogeneous decarboxylation product was not produced.Instead a mixture of hydrocarbon to breakdown products was produced andwas not identified by the authors. In general, the decarboxylation ofcarboxylic acids that do not contain other interacting functional groupsat high temperature and pressure is poorly understood in the literature.Gaining a better fundamental understanding of the chemistry andmethodologies necessary to promote decarboxylation of fatty acids, orcracking reactions to larger smaller alkanes and alkenes, may allow thefuture development of new fuel and solvent technologies. In one aspect,described herein is the thermal treatment of protonated free fatty acidsunder anoxic conditions. Processes of this nature hold the potential toproduce a higher grade fuel than the traditional biodiesels, and yetwould potentially produce higher yields of desirable products thanpyrolysis.

SUMMARY

Described herein are methods for producing fuels and solvents from fattyacid resources. Also disclosed herein are fuels and solvents produced bythe methods described herein. The advantages of the materials, methods,and articles described herein will be set forth-in part in thedescription which follows, or may be learned by practice of the aspectsdescribed below. The advantages described below will be realized andattained by means of the elements and combinations particularly pointedout in the appended claims. It is to be understood that both theforegoing general description and the following detailed description areexemplary and explanatory only and are not restrictive.

BRIEF DESCRIPTION OF FIGURES

The accompanying Figures, which are incorporated in and constitute apart of this specification, illustrate several aspects described below.

FIG. 1 shows a schematic of (a) sand bath and purge system and (b)microreactor.

FIG. 2 shows a schematic of closed microreactor.

FIG. 3 shows a schematic of the microreactor purge system.

FIG. 4 shows a sand bath system.

FIG. 5 shows a schematic of a Techne SBS-4 sand bath.

FIG. 6 shows a schematic of modified reactor for measuring internalreactor temperature.

FIG. 7 shows a schematic of the modified reactor for measuring internalreactor pressure.

FIG. 8 shows the GC-FID temperature profile for liquid analysis.

FIG. 9 shows the GC-TCD temperature profile for gas analysis.

FIG. 10 shows the internal reactor temperature during stearic acidpyrolysis as a function of time for controller set-point temperatures of370° C., 410° C., and 450° C., where the reactions were conducted in N₂atmosphere and were initially at atmospheric pressure.

FIG. 11 shows the GC-FID chromatogram of the pentane soluble pyrolysisproducts of stearic acid after 30-minute reaction times at temperaturesbetween 350° C. and 500° C., where the reactions were conducted in N₂atmosphere and were initially at atmospheric pressure.

FIG. 12 shows the GC-FID chromatogram of the pentane soluble pyrolysisproducts of stearic acid after 5-minute reaction times at temperaturesbetween 400° C. and 550° C., where the reactions were conducted in N₂atmosphere and were initially at atmospheric pressure.

FIG. 13 shows the identification of the typical ladder series formedafter heating stearic acid for 5 minutes at 500° (chromatogram in FIG.12), where the reaction was conducted in N₂ atmosphere and was initiallyat atmospheric pressure.

FIG. 14 shows the typical pentane soluble pyrolysis products of stearicacid after 5 minutes at 500° verified by running external standards,where the reaction was conducted in N₂ atmosphere and was initially atatmospheric pressure.

FIG. 15 is a GC-FID chromatogram showing the external standards run forverification of pyrolysis products, where the standards were (1) aC₈-C₂₀ alkane mixture purchased and (2) a carboxylic acid standard.

FIG. 16 is a GC-FID chromatogram showing pyrolysis products at 400° C.for 5 minutes in pentane (first extraction) and toluene (secondextraction), where the reactions were conducted in N₂ atmosphere andwere initially at atmospheric pressure.

FIG. 17 is a GC-FID chromatogram showing pyrolysis products at 450° C.for 5 minutes in pentane (first extraction) and toluene (secondextraction), where the reactions were conducted in N₂ atmosphere andwere initially at atmospheric pressure.

FIG. 18 is a GC-FID chromatogram showing the difference in productdistributions before (a) and after drying and re-suspension (b) ofstearic acid pyrolysis products for 1 hr reactions conducted at 450° C.,where the reactions were conducted in N₂ atmosphere and were initiallyat atmospheric pressure.

FIG. 19 is a GC-FID chromatogram showing the extraction solvent,pentane, and internal standard solution (nonadecanoic acid methyl esterin pentane).

FIG. 20 is a GC-FID chromatogram showing pentane soluble stearic acidpyrolysis products from a batch reaction at T=350° C. and t=4 and 8hours, where the reactions were conducted in N₂ atmosphere and wereinitially at atmospheric pressure.

FIG. 21 is a GC-FID chromatogram showing pentane soluble stearic acidpyrolysis products from a batch reaction at T=370° C. and t=1-8 hours,where the reactions were conducted in N₂ atmosphere and were initiallyat atmospheric pressure.

FIG. 22 is a GC-FID chromatogram showing pentane soluble stearic acidpyrolysis products from a batch reaction at T=390° C. and t=0.5-8 hours,where the reactions were conducted in N₂ atmosphere and were initiallyat atmospheric pressure.

FIG. 23 is a GC-FID chromatogram showing pentane soluble stearic acidpyrolysis products from a batch reaction at T=410° C. and t=0.5-8 hours,where the reactions were conducted in N₂ atmosphere and were initiallyat atmospheric pressure.

FIG. 24 is a GC-FID chromatogram showing pentane soluble stearic acidpyrolysis products from a batch reaction at T=430° C. and t=0.5-8 hours,where the reactions were conducted in N₂ atmosphere and were initiallyat atmospheric pressure.

FIG. 25 is a GC-FID chromatogram showing pentane soluble stearic acidpyrolysis products from a batch reaction at T=450° C. and t=0.5-8 hours,where the reactions were conducted in N₂ atmosphere and were initiallyat atmospheric pressure.

FIG. 26 is a GC-FID chromatogram showing pentane soluble stearic acidpyrolysis products from a batch reaction at T=500° C. and t=0.5-4 hours,where the reactions were conducted in N₂ atmosphere and were initiallyat atmospheric pressure.

FIG. 27 shows the percentage of C₈-C₂₀ alkanes formed as a function oftemperature and time.

FIG. 28 shows the percentage of C₈-C₂₀ alkenes formed as a function oftemperature and time.

FIG. 29 shows the molar yields of C₈-C₂₀ alkanes as a function oftemperature for 0.5 hr reactions

FIG. 30 shows the molar yields of C₈-C₂₀ alkanes as a function oftemperature for 1 hr reactions.

FIG. 31 shows the molar yields of C₈-C₂₀ alkanes as a function oftemperature for 4 hr reactions.

FIG. 32 shows the molar yields of C₈-C₂₀ alkanes as a function oftemperature for 8 hr reactions.

FIG. 33 shows the molar ratio of alkanes to alkenes as a function ofcarbon number and reaction time at T=390° C.

FIG. 34 shows the molar ratio of alkanes to alkenes as a function ofcarbon number and reaction time at T=410° C.

FIG. 35 shows the molar ratio of alkanes to alkenes as a function ofcarbon number and reaction time at T=430° C.

FIG. 36 shows the molar ratio of alkanes to alkenes as a function ofcarbon number and reaction time at T=450° C.

FIG. 37 shows the molar ratio of alkanes to alkenes for C₁₇ as afunction of temperature and time.

FIG. 38 shows the typical gas composition from stearic acid pyrolysisfrom a 1 hr reaction at 410° C. as analyzed on GC-TCD.

FIG. 39 shows methane (CH₄), carbon dioxide (CO₂), and air standards asanalyzed on GC-TCD.

FIG. 40 shows the percent of gas products formed during 1 hr stearicacid pyrolysis reactions as a function of temperature, where the initialpressure was atmospheric and the reactions were conducted in N₂.

FIG. 41 shows the percent of liquid products formed during stearic acidpyrolysis as a function of temperature and time, where the initialpressure was atmospheric and the reactions were conducted in N₂.

FIG. 42 shows the percentage of initial stearic acid feed that wasconverted during 1 hr pyrolysis reactions as a function of temperature,where the initial pressure was atmospheric and the reactions wereconducted in N₂.

FIG. 43 is a chromatogram (GC-FID) showing stearic acid pyrolysisproducts after a 4 hr reaction at 255° C., where the initial pressurewas atmospheric and the reactions were conducted in N₂.

FIG. 44 is a chromatogram (GC-TCD) showing gaseous reaction productsafter a 4 hr reaction at 255° C., where the initial pressure wasatmospheric and the reactions were conducted in N₂.

FIG. 45 is a chromatogram (GC-FID) showing oleic acid pyrolysis productsafter a 1 hr reaction at 410° C., where the initial pressure wasatmospheric and the reactions were conducted in N₂.

FIG. 46 shows the main products of oleic acid pyrolysis after 1 hr at410° C.

FIG. 47 are duplicate chromatograms (GC-TCD) showing the gas productsfrom oleic acid pyrolysis after 1 hr at 410° C., where the initialpressure was atmospheric and the reactions were conducted in N₂

FIG. 48 is a chromatogram showing canola oil hydrolysates.

FIG. 49 is a TLC-FID chromatogram showing the bleached fancy tohydrolysates.

FIG. 50 is a TLC-FID chromatogram showing the oleic acid standardmixture.

FIG. 51 is a TLC-FID chromatogram showing the oleic acid standardmixture spiked with bleached fancy hydrolysates (1:1 by volumestandard:sample).

FIG. 52 is a TLC-FID chromatogram showing the oleic acid standardmixture spiked with bleached fancy hydrolysates (2:1 by volumestandard:sample).

FIG. 53 is a GC-FID chromatogram showing poultry tallow pyrolysisproducts from a 4 hr reaction at 410° C., where reactions were conductedin N₂ atmosphere and were initially at atmospheric pressure.

FIG. 54 is a GC-FID chromatogram showing poultry tallow pyrolysisproducts from a 4 hr reaction at 410° C. after a water extraction step,where the reactions were conducted in N₂ atmosphere and were initiallyat atmospheric pressure.

FIG. 55 is a GC-FID chromatogram showing canola tallow pyrolysisproducts from a 1 hr reaction at 410° C., where the reactions wereconducted in N₂ atmosphere and were initially at atmospheric pressure.

FIG. 56 is a GC-FID chromatogram showing bleached fancy pyrolysisproducts from a 1 hr reaction at 390° C., where the reactions wereconducted in N₂ atmosphere and were initially at atmospheric pressure.

FIG. 57 is a GC-FID chromatogram showing bleached fancy hydrolysatesfrom a 1 hr reaction at 410° C. dissolved in pentane, where thereactions were conducted in N₂ atmosphere and were initially atatmospheric pressure.

FIG. 58 is a GC/MS chromatogram showing derivatized and underivatizedsamples of bleached fancy pyrolysis products after 1 hr reaction at 410°C.

FIG. 59 is a GC/MS chromatogram showing derivatized bleached fancypyrolysis products after 1 hr reaction at 410° C.

FIG. 60 is an expanded region of GC/MS chromatogram showing derivatizedbleached fancy pyrolysis products after 1-hour reaction at 410° C.

DETAILED DESCRIPTION

Before the present materials, articles, and/or methods are disclosed anddescribed, it is to be understood that the aspects described below arenot limited to specific compounds, synthetic methods, or uses as suchmay, of course, vary. It is also to be understood that the terminologyused herein is for the purpose of describing particular aspects only andis not intended to be limiting.

In this specification and in the claims that follow, reference will bemade to a number of terms that shall be defined to have the followingmeanings:

Throughout this specification, unless the context requires otherwise,the word “comprise,” or variations such as “comprises” or “comprising,”will be understood to imply the inclusion of a stated integer or step orgroup of integers or steps but not the exclusion of any other integer orstep or group of integers or steps.

It must be noted that, as used in the specification and the appendedclaims, the singular forms “a,” “an” and “the” include plural referentsunless the context clearly dictates otherwise. Thus, for example,reference to “an oil” includes a single oil or mixtures of two or moreoils.

“Optional” or “optionally” means that the subsequently described eventor circumstance can or cannot occur, and that the description includesinstances where the event or circumstance occurs and instances where itdoes not.

Described herein are methods for producing fuels and solvents from fattyacid resources. In one aspect, the method comprises:

-   a. separating one or more fatty acids from the fatty acid resource;    and-   b. converting the fatty acid to one or more alkanes, alkenes, or a    mixture thereof.

The term “fatty acid resource” as defined herein is any source of freefatty acid or a precursor to a free fatty acid upon subsequentprocessing. For example, a triglyceride is a precursor to a free fattyacid, where hydrolysis of the glycerol group produces the free fattyacid. Examples of fatty acid resources include, but are not limited to,vegetable oil, animal fats, spent cooking oil, lipids, phospholipids,soapstock, or other sources of triglycerides, diglycerides ormonoglycerides. In one aspect, the vegetable oil comprises corn oil,cottonseed oil, canola oil, rapeseed oil, olive oil, palm oil, peanutoil, ground nut oil, safflower oil, sesame oil, soybean oil, sunfloweroil, algae oil, almond oil, apricot oil, argan oil, avocado oil, benoil, cashew oil, castor oil, grape seed oil, hazelnut oil, hemp seedoil, linseed oil, mustard oil neem oil, palm kernel oil, pumpkin seedoil, rice bran oil, walnut oil, a combination thereof. In anotheraspect, the animal fat comprises blubber, cod liver oil, ghee, lard,tallow, derivatives thereof (e.g., yellow grease, used cooking oil,etc.), or a combination thereof.

It is contemplated that the fatty acid resource can be further purifiedprior to separation step (a). For example, the fatty acid resource canbe distilled or extracted to remove any undesirable impurities. In thealternative, the fatty acid resource can be used as-is and proceed toseparation step (a). The source of the fatty acid resource willdetermine if any pre-purification steps are required.

Separation step (a) involves removing or isolating one or more fattyacids from the fatty acid resource. A number of different techniques areknown in the art for the isolation and purification of fatty acids. Forexample, U.S. Pat. No. 5,917,501 discloses a process for isolating fattyacids. The process involves hydrolyzing a naturally occurring lipidmixture containing phospholipids, triglycerides, and sterols to form atwo-phase product containing a fatty acid phase comprised of free fattyacids and sterols, and an aqueous phase comprised of water, glycerol,and glycerol phosphoric acid esters. The aqueous phase is separated fromthe fatty acid phase and the crude fatty acid phase is heated to convertthe free sterols to fatty acid sterol esters. The free fatty acids aredistilled from the fatty acid sterol esters to yield purified fattyacids, which are free of cholesterol and other sterols, and phosphorouscompounds. In other aspects, the fatty acid resource is exposed to acidin order to hydrolyze a fatty acid precursor present in the fatty acidresource to produce the corresponding fatty acid. For example, vegetableoils are rich in triglycerides, which upon acid hydrolysis, produce thefree fatty acid and glycerol.

After the separation step, it is desirable to produce a pure orsubstantially pure form of the fatty acid. The phrase “substantiallypure” as used herein is defined as greater than 90% by weight fatty acidcontent. The presence of impurities can adversely affect the finalcomposition of the fuel or solvent. For example, if sulfur, oxygen, ornitrogen compounds are present in the fatty acid prior to step (b), toundesirable product characteristics result including high sulfur ornitrogen emissions during combustion or side-reactions may occur duringstep (b) such as the formation of undesirable aromatic compounds.

The nature of the fatty acid will vary depending upon the fatty acidresource. The fatty acid can be a saturated fatty acid, an unsaturatedfatty acid, or a combination thereof. Examples of fatty acids include,but are not limited to, butyric acid, lauric acid, myristic acid,palmitic acid, stearic acid, arachidic acid, alpha-linolenic acid,docosahexaenoic acid, eicosapentaenoic acid, linoleic acid, arachidonicacid, oleic acid, erucic acid, a naturally derived fatty acid from aplant or animal source, or a combination thereof. It is contemplatedthat the fatty acid can be the free acid or the salt/ester thereof. Thefatty acid can also be a mixture of fatty acids.

The second step involves converting the fatty acid(s) to one or morealkanes, alkenes, or mixtures thereof. In general, during the conversionstep, the fatty acids are decarboxylated and cracked to produce CO₂ andthe alkanes or alkenes. The length of the alkane or alkene chain willvary depending upon the fatty acid and reaction parameters, which willbe discussed in detail below. In general, the alkanes and alkenes arefrom C₁ to C₂₀ hydrocarbons. For example, decarboxylation of stearicacid, which has the formula CH₃(CH₂)₁₆COOH, produces CH₃(CH₂)₁₅CH₃,shorter alkanes and alkenes, and CO₂.

In one aspect, the conversion of the fatty acid to the alkane and/oralkene comprises heating the fatty acid to convert all or substantiallyall of the fatty acid to an alkane, an alkene, or a mixture thereof. Thetemperature of the heating step can vary amongst different parameters.In one aspect, the temperature of the heating step is from 220° C. to650° C., 300° C. to 650° C., 350° C. to 650° C., 350° C. to 600° C., or250° C. to 500° C. Other parameters to consider are the duration of theheating step and the pressure at which the heating step is conducted.The pressure can range from ambient to 2,000 psi, and the duration ofthe heating step can be from seconds up to 12 hours. In one aspect, theheating step is from two seconds up to 8 hours. In another aspect, theheating step is performed under an inert atmosphere such as, forexample, nitrogen or argon.

By varying reaction conditions during the conversion of the fatty acidto the alkane/alkene, one of ordinary skill in the art can produce shortor long chain alkanes/alkenes for fuels and solvents. For example,prolonged heating at elevated temperatures can produce short chainalkanes/alkenes that can be useful as fuels. Alternatively, long chainalkanes/alkenes can be produced by one of ordinary skill in the art byreducing the heating time and temperature. If short chain alkanes oralkenes are produced, reaction conditions can be controlled such thatthese products are gasses (e.g., methane, propane, butane, etc.) thatcan be readily removed from the reactor.

In another aspect, the use of a decarboxylation catalyst can be used tofacilitate the conversion of the fatty acid to the alkane or alkene.Depending upon the selection of the decarboxylation catalyst, thecatalyst can reduce the heating temperature and time. This is desirablein certain instances, particularly if degradation of the alkane/alkeneor side reactions (e.g., aromatization) are to be avoided. Examples ofdecarboxylation catalysts include, but are not limited to, activatedalumina catalysts.

Steps (a) and/or (b) can be performed in batch, semi-batch, orcontinuous modes of operation. For example, with respect to step (b), acontinuous reactor system with unreacted acid recycle could be employedto enhance the yield of desirable alkane/alkene by limiting the durationand exposure of the alkane/alkene in the high temperature reactor.Carbon dioxide and small hydrocarbon products could be recovered, withthe gas phase hydrocarbons used as fuel for the reactor or otherapplications. When a continuous reactor system is used, processconditions can be optimized to minimize reaction temperatures and timesin order to maximize product yields and composition. As the reaction canbe adjusted to select for a preferred carbon chain length (long, shortor medium), the technology has the capability of enriching for aparticular product group. From these groups, individual chemicals couldbe recovered, purified, and sold as pure platform chemicals.

The methods described herein provide numerous advantages over currenttechniques for producing bio-fuel. As described above, the methodsdescribed herein can be used to produce either solvents or fuels thatare similar to tradiational diesel fuel. The methods utilize renewableresources to create a non-petroleum based sustainable fuel source freeof aromatic compounds. The products formed are chemically much moreuniform than other high temperature processes currently used. Forexample, the fuels or solvents produced herein are substantially free ofaromatic to compounds, where the term “substantially free” is defined asless than 5% by weight aromatic compounds. It is also contemplated thatno aromatic compounds are present in the fuels or solvents. It isanticipated the methods described herein will provide higher productyields than other pyrolysis technologies and will produce a fuel muchmore similar to diesel than biodiesel. The products will not have theproblems of biodiesel in that they will be oxidatively stable and willhave pour points similar to conventional diesel fuel. Finally, the inputcosts are expected to be lower using the methods described herein whencompared to competitive, existing biodiesel technologies. In particular,the process does not require a hydrogenation step to producehydrocarbons, which adds significant cost to the process.

EXAMPLES

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how thematerials, articles, and methods described and claimed herein are madeand evaluated, and are intended to be purely exemplary and are notintended to limit the scope of what the inventors regard as theirinvention. Efforts have been made to ensure accuracy with respect tonumbers (e.g., amounts, temperature, etc.) but some errors anddeviations should be accounted for. Unless indicated otherwise, partsare parts by weight, temperature is in ° C. or is at ambienttemperature, and pressure is at or near atmospheric. There are numerousvariations and combinations of reaction conditions, e.g., componentconcentrations, desired solvents, solvent mixtures, temperatures,pressures and other reaction ranges and conditions that can be used tooptimize the product purity and yield obtained from the describedprocess. Only reasonable and routine experimentation will be required tooptimize such process conditions.

I. Materials and Chemicals

The chemicals used in the investigation, excluding the reactorfeedstocks below, are listed in Table 1.

The feedstocks used in these experiments included:

(1) Stearic acid (95%) purchased from Sigma (St. Louis, Mo.)

(2) Oleic acid purchased from Sigma (St. Louis, Mo.)

(3) Poultry tallow from Lomax Inc. (Montreal, Quebec)

(4) Bleached fancy (BF)

(5) Yellow grease (YG)

(5) Canola oil purchased locally from a Canadian Department Store.

Table 2 shows the fatty acid composition of the feed fats and oil. Table3 shows the percentage of saturated and unsaturated fatty acid in feedfats and oil.

II. Experimental Equipment Microreactors and Sand Bath

Pyrolysis reactions were conducted in 15 ml batch microreactors (alsoreferred to as the reactors) heated with a fluidized sand bath as shownin FIG. 1. The experimental set-up consisted of three main componentsincluding:

-   (1) stainless steel microreactors;-   (2) microreactor purge system; and-   (3) fluidized sand bath system for heating.

Batch Microreactors

The 15 ml microreactors used in these experiments were constructed withstainless steel (S.S.) Swagelok® fittings and tubing. A schematic of theclosed microreactor is shown in FIG. 2. The microreactors consisted of abottom cap, central tube, and a top cap with a ¼″ opening. Stainlesssteel tubing (⅛″), approximately 15 cm in length, was connected to thisopening with a reducing union and a needle valve was situated near theend of this tube (approximately 13 cm above the reactor top) to open andclose the reactor. A mount (not shown in schematic) was also attached tothis tubing so that the microreactors could be attached to the sand bathsystem.

Replacing the Reactors

The microreactors were used until they could not be properly sealed orseized during the reaction and could not be opened, at which time theywere replaced. Typically, microreactors lasted between 10-20 reactions.

Microreactor Purge System

The microreactor design allows for connection to a gas cylinder forpressurization or purging. A schematic of the microreactor purge systemused in this work is shown in FIG. 3. The pressure was set by reading P1and adjusting the tank regulator. The microreactors were connected tothe purge system and V₁, V₂ and the microreactor valve (not shown onschematic) were opened to allow nitrogen into the reactor.

Sand Bath System

The microreactors were heated in a Techne Model SBS-4 fluidized sandbath (Burlington, N.J.). The main components of the sand bath system arehighlighted in FIG. 4 and include the sand bath, motor and arm, airsupply, and temperature controller. A schematic of the sand bath isshown in FIG. 5 and its dimensions are presented in Table 4. The sandbath was filled to approximately 1-2″ below the top with aluminum oxidesand. To fluidize the sand, compressed air was blown into the bath nearthe bottom and through a porous plate for more uniform air distribution.A Techne TC-8D temperature controller (Burlington, N.J.) was used tomaintain the bath at a constant temperature throughout the reaction. Thetemperature of the bath was measured by a K-type thermocouple locatednear the center of the bath. The heating elements were located at thebottom of the sand bath, above the porous plate. An off-center wheelconnected to a motor and arm was used to agitate the microreactor forthe duration of the reaction.

Modified Reactors for Measurement of Internal Reaction Conditions

The batch microreactors were modified to allow measurement oftemperature and pressure inside the reactors during the reaction runs. A1/16″ K-type thermocouple (Aircom Industries, Edmonton, AB) was insertedthrough the top of one of the reactors so the tip was situatedapproximately 1 mm above the reactor bottom. The thermocouple wasconnected to the reactor mount tubing using Swagelok® fittings as shownin FIG. 6. The thermocouple was connected to a Digi-Sense Dual JTEKthermocouple thermometer (Cole-Parmer Instrument Company, Vernon Hills,Ill.) to measure the temperature. FIG. 7 shows a second modified reactorfor measuring pressure. A Swagelok® pressure gauge (Swagelok, Edmonton,AB) was attached to the reactor mount tubing with Swagelok® fittings.

III. Experimental Procedure Pyrolysis Reactions

All pyrolysis reactions were conducted in the microreactors. Prior toloading the reactors, the fluidized sand bath was turned on and thetemperature controller was set to the desired temperature for thatparticular reaction. The airflow into the reactor was adjusted so thatthe sand fluidized enough to form bubbles 1-2″ in diameter or just evenwith the top of the sand bath. The sand bath was allowed to heat upuntil it reached the steady state temperature as determined by a stabletemperature reading on the controller for at least 15 minutes. Heatingtimes ranged between 1.5 and 2.5 hours depending on the set temperature.As the sand bath heats, the air also heats and expands causing theamount of fluidization and the bubble size to increase. To keep thebubble size constant, the airflow was adjusted manually throughout theheating process.

Between reactions the microreactors were scrubbed thoroughly with metalbrushes, washed with soap and water, and rinsed with distilled water andwash acetone to ensure they were completely clean and free of residuefrom the previous reaction. After the microreactors were completely dry,feedstock was weighed into the reactor. Anti-seize lubricant was appliedto the threading on the reactor cap and the reactor was closed andtightened. The microreactor was connected to the nitrogen purge system,all valves were opened, and the microreactors were tested for leaksusing Swagelok Snoop®. If a leak was detected, the microreactor wasremoved from the purge system and re-tightened. If a seal could not beobtained after being re-tightened several times, the microreactor wasreplaced. Once the microreactor was completely sealed and free of leaks,it was purged three times (filled and emptied) before closing themicroreactor valve and disconnecting from the purge system.

Once the microreactor was prepared for the reaction, it was attached tothe sand bath rod and lowered into the center of the sand bath. Theposition of the microreactors on the rod was kept constant so that themicroreactors were always in approximately the same location in thebath. The microreactors were positioned so they did not contact any partof the sand bath and were completely immersed in the sand. The motor wasswitched on and timing of the reaction commenced when the to arm beganagitating. Upon completion of the reaction, the microreactors werelifted from the sand bath and immediately quenched in a bucket of roomtemperature water to end the reaction. The reactors were vented in thefumehood to release any gaseous products formed during the reactions andopened for extraction unless the gas products were collected foranalysis as described below.

To measure the internal reactor temperature and pressure reactors wereloaded and purged as normal, however, the modified reactor mountsdescribed below were used. The temperature was recorded by reading thedigital thermometer every 30 seconds for the first 10 minutes of thereaction, at every minute from 10-15 minutes and then again at 30, 45,and 60 minutes. The pressure was recorded throughout the run as well asafter quenching to determine the amount of pressure generated from theformation of gaseous product.

Extraction of Reaction Products

The reaction products were extracted from the microreactor using 10 mlof pentane spiked with internal standard unless otherwise specified.Nonadecanoic methyl ester was used as the internal standard and wasprepared with pentane in concentrations of approximately 0.5 or 1 mg/ml.The pentane/internal standard mixture was measured into the microreactorusing a displacement pipette and stirred so that any solid material inthe microreactor was scraped off the microreactor sides and brokenapart. After approximately 15 minutes, the liquid extract wastransferred to a sample vial. All products were stored in dram vialswith screw tops and Teflon® liners and stored at 4° C.

Nonadecanoic acid was chosen as an internal standard because it issimilar in structure to the starting compound. When this standard wasrun on GC-FID it gave a sharp clean peak and did not overlap with any ofthe potential pyrolysis products.

Gas Chromatography (GC)

Liquid Extracts

The pentane extracts were analyzed on a Varian 3400 Gas Chromatographequipped with a Varian 8200 auto-sampler (Palo Alto, Calif.) coupledwith a flame-ionizing detector (FID) operated at 320° C. An RH1 columnfrom Rose Scientific (Mississauga, Ontario, Calif.) was used for allanalyses and the injection volume remained constant at 1 μl. Thetemperature profile is shown in FIG. 8. The initial column temperaturewas set at 35° C. and programmed to increase to 280° C. at a rate of 10°C./min It was held at the final temperature for 5.4 minutes, for a totalrun time of 29.9 minutes.

Two external standards were run for product verification. These were (1)a C₈-C₂₀ alkane mixture (Fluka) and (2) a C3:0-C20:0 carboxylic acidmixture prepared in-house using carboxylic acids purchased from Sigma.These internal standards were run throughout the GC analysis to accountfor potential shifting of the peaks.

Gaseous Samples

To collect gas samples from the microreactor for analysis, a ¼ Swagelok®tube fitting with a septum was screwed into the fitting used to connectthe microreactor to the purge system. A glass syringe and needle wasinserted through the septum and the reactor valve was opened. Four ml ofgas was drawn from the reactor using the syringe and expelled into a 5ml vacutainer. This was repeated for a total of 8 ml of gas product ineach 5 ml vacutainer. Gas fractions were analyzed on a Hewlett PackardSeries II 5890 gas chromatograph coupled to a TCD (total compositiondetector) set at 80° C. 100 μL of the sample was manually injected ontoa 30 m Agilent HP-plotq column with an I.D. of 0.53 μm. The temperatureprogram used is shown in FIG. 8. Select gas samples were also run onGC-FID at the conditions outlined below.

Gas Chromatography-Mass Spectrometry (GC-MS)

Preliminary GC-MS analyses were conducted on select samples using aWaters (formerly Micromass, Milford, Mass.) Trio 2000 equipped with aHP5890 Series II GC in the University of Alberta's Chemistry Department.The temperature profile used was the same as shown in FIG. 8.

Extent of Reaction

To determine the extent of reaction it was necessary to dissolve all ofthe stearic acid feed remaining in the reactor. Chloroform was used asan extraction solvent because of the relatively high solubility ofstearic acid in this solvent compared to pentane. Reaction products werewashed out of the microreactors with chloroform into a round bottomflask until no product remained inside the reactor. The chloroform wasthen removed by roto-evaporation. During the evaporation/drying process,it is likely that some of the volatile products were lost, but becauseit is only the stearic acid that will be quantified, this should notaffect the result. Thirty ml of chloroform spiked with internal standardwas pipetted into the flask with the remaining products and swirleduntil all of the product had dissolved. Based on the solubility ofstearic acid in chloroform, 30 ml is more than sufficient to dissolvethe maximum possible stearic acid product (1 gram if no reactionoccurred). Samples were taken and stored at 4° C. in dram vials withTeflon liners until analysis. Controls were conducted using theextraction procedure with no thermal treatment.

Derivatization with Diazomethane

A 250 μl aliquot of sample was added to a one dram vial and completelydried under N₂ before excess amounts of diazomethane, prepared in-house,was added to the vial. After the reaction was complete (i.e. no morebubble formation), the sample was dried again with N₂ and thenresuspended with a known volume of chloroform before analysis on GC.

Percentage of Liquid and Gas Fractions

To get a crude estimate of the liquid yield, the reactor was opened andthe liquid product was extracted with a Pasteur pipette and weighed. Toget a crude estimate of the mass of the gas product, the reactor wasweighted before and after venting the gas. For these reactions, 5.0 g ofstearic acid were used as feed instead of the typical 1.0 g so that thedifference could be readily measured.

Hydrolysis Reactions

Before the crude and vegetable oils were pyrolyzed, they were firsthydrolyzed. Small-scale hydrolysis reactions were conducted in the samemicroreactors as the pyrolysis reactions. Approximately 3 grams oftallow or oil and 6 grams of distilled water were added to themicroreactors for a 1:2 ratio (by weight) of oil/tallow to water. Thereactors were sealed as described previously and pressurized with N₂ to3.48 MPa (500 PSI). The hydrolysis reaction was conducted at 250° C. for4 hours. When the reactors were opened, they were placed in a beaker ofhot water so that the products remained in liquid state and weretransferred to a glass sample vial with a Pasteur pipette. The fat layerwas allowed to separate from the glycerol/water layer and was pipettedinto a separate glass vial. Samples were stored at 4° C. until pyrolysisor derivatization. It was assumed that if any water remained in thesample, the rate of hydrolysis would be negligible at this lowtemperature. This fat or oil layer will herein be referred to as the oilor fat hydrolysates, so as not to confuse these products with theproducts formed after pyrolysis (i.e. the pyrolyzates or pyrolytic oil).

Fatty Acid Composition of the Feed

The fatty acid composition of the yellow grease tallow, bleached fancytallow, poultry tallow, and canola oil was determined by derivatizingsamples with boron-trifluoride and analyzing them on GC-FID. Thederivatization procedure is outlined below and the GC analysis was thestandard fatty acid protocol as described above.

Derivatization with Boron Trifluoride

For derivatization with boron trifluoride, approximately 30 mg of samplewas weighed into a test tube and 5 mL of a 14% borontrifluoride-methanol/methanol/hexane mixture (35:45:20 V:V:V) was added.The tubes were tightly sealed and heated in boiling water for 45minutes. After the tubes had cooled, 4 mL of water and 4 mL of hexanewere added and the tube was shaken for 1-2 minutes. The layers wereallowed to separate and the hexane layer was extracted with a Pasteurpipette and stored in a dram vial with Teflon liner at 4° C. untilanalysis.

Analysis of Hydrolysates Using TLC-FID

The composition of the hydrolysates was determined using thin layerchromatography coupled with an FID detector (TLC-FID). Samples wereprepared for analysis by weighing approximately 0.03 g of the fattyhydrolysates into a screw cap vial and adding 5 ml of HPLC grade hexane.A specific volume of sample was spotted on silica gel Chromarods-SIIIusing a needle and syringe in 0.2 μL increments. The rods were thenplaced in a developing tank containing a mixture of hexane/diethylether/acetic acid (80:20:1 V:V:V) for 20 minutes and dried at 120° C.for 10 minutes. Lipid analysis was conducted using an Iatroscan TH-10(IARON-Laboratories Inc., Tokyo, Japan) with a hydrogen pressure of 113kPa, air flow rate of 2000 mL/min, and a scan speed of 30 s/rod. Areference standard containing 25% (w/w) each of oleic acid, monoolein,diolein and triolein was obtained from Nu-Chek Prep Inc. (Elysian,Minn.).

Analysis of Hydrolysates Using GC-FID

To determine the composition of unreacted or non-hydrolyzed feed, ifany, GC-FID analysis was conducted using derivatized samples. Bleachedfancy hydrolysates were derivatized by four different methods, whichonly methylate specific groups as outlined in Table 5. Diazomethanederivatization was conducted using the procedure outlined above. Theother three methods are discussed below.

Derivatization with Sodium Methoxide and Methanolic HCL

The same procedure was used for derivatization with sodium methoxide andmethanolic HCL. A 10-30 mg oil or fat sample was weighed into the bottomof a test tube with 50 μL of benzene to solubilize the sample. Thesample was allowed to sit for 20-30 minutes before 2 mL of either sodiummethoxide or methanolic HCL was added to the test tube. The samples werethen heated in a water bath (30 minutes for sodium methoxide, 50 minutesfor methanolic HCL) at 50° C. The samples were allowed to cool before100 μL of water and 2 mL of hexane were added to the test tubes. Thetubes were shaken and allowed to sit while the organic and aqueouslayers developed. The hexane (organic) layer was extracted and stored ina vial with a Teflon® liner at 4° C.

IV. Internal Reactor Temperature and Pressure for the Techne SBS-4 SandBath

Temperature profiles representing heating of the microreactors at 370,410, and 450° C. are presented in FIG. 10. The data represents theaverage between duplicate runs and the error bars (not visible)represent the standard error between these runs. The heating rate of thematerial inside the reactor appears to be fairly rapid as the reactortemperature, T_(reactor), reaches 95% of the setpoint temperature(referenced from the starting temperature at time zero and shown on FIG.10 as the dashed line) within 3.5, 3, and 4 minutes for the threesetpoint temperatures, respectively. As expected, there is a drop in thecontroller temperature (solid line), at all three temperatures, afterthe reactors are dropped in the bath. At 370° C. it took approximately 6minutes for the bath to heat back up to 370° C. while at 410° C. it took5.5 minutes. It took between 12-14 minutes for the bath to heat back upto temperature during the runs conducted at 450° C.

The pressure gauge was checked throughout the reaction run, however theset-up made it difficult to read due to the agitation. At 370° C. one ofthe reaction runs resulted in no pressurization during the reaction butthe second run resulted in a maximum pressure of 1,034 kPa (150 PSI). Inboth cases, the pressure gauge indicated zero pressure after quenching.At 450° C., the maximum pressure reached during separate runs was 2,586kPa (375 PSI) and 3,103 kPa (450 PSI). After quenching, there wasapproximately 689 kPa (100 PSI) of pressure in the reactors. At 410° C.,one of the runs exhibited an extremely large pressure increase at theend of the run to 4482 kPa (650 PSI). After quenching, the pressureinside the reactor was 689 kPa (100 PSI). Based on the results of theother runs, this appears to be unusual. The second run at 410° C.yielded results that would be expected based on the other temperatures.A maximum pressure of 1379 kPa (200 PSI) was reached but afterquenching, the gauge indicated zero pressure inside the reactor.

V. Model Compound Work Preliminary Pyrolysis Studies

The experimental set-up for the preliminary pyrolysis reactions is shownin Table 6. All reactions were conducted in nitrogen and were initiallyat atmospheric pressure Immediately after quenching, the reactor wasopened and 10 ml of pentane was added to the products, swirled, and thepentane soluble products were extracted with a pipette into a flask. Twosubsequent 10 ml extractions were also conducted for a total of 3×10 mlextractions before an aliquot was transferred to a sample vial with aTeflon® lined screw cap. For this set of runs, no internal standard wasadded but unreacted stearic acid was analyzed as a control. The liquidextracts were analyzed on GC-FID. The results are shown in FIGS. 4.2 and4.3. Duplicate chromatograms to (not shown) are very similar for all thetemperatures, indicating good consistency between reaction runs.

FIGS. 11 and 12 show that product distribution changes substantiallywith temperature and time. A 30-minute reaction at 350° C. (FIG. 11),results in little reaction as indicated by the absence of peaks incomparison to the other runs and the relatively large peak that wasidentified as the starting material, stearic acid. This was determinedby comparing retention times of a sample of stearic acid in pentane withno thermal treatment. At 400° C., a distinct series of ladders begins toform and at 450° C., these ladder series continue to develop. At 500°C., these ladders begin to degenerate resulting in numerous peakscluttered at low retention times. The same trend is evident for the 5minute reactions but at slightly higher temperatures. At 400° C. (FIG.12) the ladders are just starting to develop and increase in size atboth 450° C. and 500° C. Although the ladders are still present at 500°C., more peaks are starting to form at retention times less than 5minutes. At 550° C., these ladders have completely degenerated andresult in a similar looking distribution as the 30-minute reaction at500° C.

Identification of Peaks

GC/MS Analysis

The following samples were analyzed by mass spectrometry: (1) stearicacid breakdown products after a 5-minute reaction at 500° C.(chromatogram shown in FIG. 12) and (2) stearic acid breakdown productsafter a five minute reaction at 550° C. (chromatogram shown in FIG. 12).A search was conducted using the NIST (National Institute of Standardsand Technology) mass spectra library and the best spectra matches weredetermined. The results show that after five minutes at 500° C., fourseries or ladders were formed including an alkane series, an alkeneseries, a carboxylic acid series, and an unsaturated carboxylic acidseries with one double bond. The spectra indicate that it is likely thatthe double bond in the alkenes is at the one position and in theunsaturated carboxylic acids, is at the end position opposite thecarboxyl group, however, this was not confirmed by NMR (nuclear magneticresonance). These ladders are illustrated in FIG. 13. The results of theNIST search at 550° C. indicated that many of the compounds were likelyaromatic.

Product Verification Using External Standards on GC-FID

FIG. 14 shows a chromatogram of the breakdown products of stearic acidafter a 5-minute reaction at 500° C. The compounds labeled were verifiedusing external standards coupled with the results from the GC/MS. Twoexternal standards including (1) a mixture of C₈-C₂₀ alkanes purchasedfrom Fluka and (2) a mixture of carboxylic acids prepared in-house usingcarboxylic acids from Sigma, were run on GC-FID using identicalconditions. The resulting chromatogram is shown in FIG. 15. A series ofalkanes from octane (C₈) to heptadecane (C₁₇) as well as a series ofcarboxylic acids between C7:0 (heptanoic acid) and C18:0 (stearic acid)were identified in the pyrolysis mixture.

Pyrolysis with a Second Extraction Using Toluene

After the pentane extraction, there was still some material in thereactor. It is possible that this material is not soluble in pentane orthat the solubility limit of the pentane had been reached. In otherwords, it was saturated with product and unable to dissolve anythingmore. Stearic acid is only somewhat soluble in pentane so it is possiblethat unreacted feed was also present in the reactor after the pentaneextraction. In order to determine what types of products were still inthe microreactor after the pentane extraction, a subsequent 3×10 mltoluene extraction was conducted for the 5-minute runs and collected foranalysis. Select chromatograms are presented in FIGS. 16 and 17. FIG. 16shows that the toluene extract contains only the starting stearic acidcompound. The smaller peaks on either side of the largest peaks areimpurities in the feedstock material (determined by running controlswith no thermal treatment) and the peaks at retention times less than 10minutes are impurities in the toluene (determined by running toluenethrough the GC). The reactor appeared to be empty after the tolueneextraction indicating that the pentane dissolved all of the reactionproducts except for some of the uncreated acid feed. The results aresimilar at 450° C. (chromatograms not shown). At 500° C., more productwas produced and there is less unreacted feed. At these conditions, thepentane dissolved the majority of the reactor products including all ofthe unreacted feed as shown by the absence of any compounds in thetoluene fraction.

Effect of Drying Down Samples on the Product Profile

For mass balance and quantification, the weight of the pentane solubleproduct is most easily determined by drying down the sample undernitrogen gas and then weighing The problem with this method is that manyof the reaction products are volatile and have the potential to beevaporated during the dying process. Before developing extractionmethodologies, it was of interest to determine if drying under nitrogenaffected the product profile. Duplicate reactions were conducted for onehour at 450° C. and 500° C. The reactors were purged with nitrogen gasand were initially at atmospheric pressure. Ten ml of pentane was usedto extract the reaction products and two 4 ml aliquots were transferredinto sample vials. One of the samples was analyzed as-is while the othersample was dried down with nitrogen and then re-suspended with 4 ml ofpentane before analysis. FIG. 18 shows chromatograms before and afterdrying at 450° C. The quantities and distribution of products changessubstantially with drying, especially the lower retention compounds. At500° C., where the products are mostly light ends and possiblyaromatics, the drying process evaporates the majority of the compounds.

Pyrolysis at Different Times and Temperatures

Numerous reactions were conducted at various temperatures and times.These were conducted to see time and temperature effects on thepyrolysis products at a broader range of conditions as well as to modifythe extraction procedure. A variety of runs were conducted attemperatures between 350-500° C. and times ranging from 1 to 6 hours.Results from these experiments helped select the conditions used for alarger time/temperature experiment.

Effects of Time and Temperature on Pyrolysis Products of Stearic Acid

Based on the results from the preliminary experiments, it was ofinterest to study the pyrolysis products of stearic acid over a widerrange of temperatures and times to determine within which of theseconditions the products of interest are formed. In this experiment,reactions were conducted at temperatures between 350-500° C. and timesranging from 0.5-8 hours. The times and temperatures chosen for thisstudy were based on preliminary results and are outlined in Table 7. Theconditions range from mild, where very little reaction took place tomore severe where there is a substantial product breakdown and where theladder series discussed in previous sections have degenerated. It iswithin these conditions that the products of interest are formed. Allreactions were conducted in nitrogen atmosphere and the microreactorswere initially at atmospheric pressure.

Product Distributions at Different Times and Temperatures

For these reactions, nonadecanoic acid methyl ester was added as aninternal standard at known concentrations. At the GC conditions used inthis experiment, the nonadecanoic acid methyl ester elutes from thecolumn at approximately 22.6 minutes as shown in FIG. 19. FIGS. 20-26show the chromatograms from the reactions conducted at the conditionsoutlined in Table 7. These chromatograms give a good “snapshot profile”of the product distribution at various conditions. Due to the nature ofthe extraction solvent and the extraction method, it is possible thatnot all of the stearic acid, which is not very soluble in pentane, andheptadecane (C₁₇ alkane), which is solid at room temperature, wasdissolved in the pentane. It is likely that these peaks areunderestimated. In terms of the types of products formed at the variousconditions, duplicate chromatograms (not shown) were virtuallyidentical. The results from this experiment confirm previous results.Both time and temperature are shown to have a substantial effect on theproduct distribution. At 350° C. (FIG. 20), the main product isheptadecane (C₁₇ alkane). The alkane ladders are just starting to format 4 hours and are slightly more developed at 8 hours. There is alsosome starting feed material remaining, however, the actual quantitycannot be estimated from the size of the peak area as explainedpreviously. Analysis of the amount of unreacted feed at differentconditions is discussed in later sections. As temperature and timeincrease, the development of the ladder series is evident. At 390° C.and 8 hours, 410° C. and 1, 4, and 8 hours, and 430° C. at 0.5 and 1hour, these ladders appear to be the most developed. At 430° C., thereis evidence of low retention compounds, possibly aromatics, starting todevelop. At 450° C. after 4 hours and at 500° C., the ladder series havedegenerated.

Estimation of C₈-C₂₀ Alkanes and Alkenes

The main products of interest are the alkanes and alkenes. Thesecompounds form the two most prominent ladder series in the pyrolysisproducts Alkanes and alkenes from C₈-C₂₀ were identified on thechromatograms using the GC/MS data and external standards. Peak areaswere used to semi-quantitatively determine the amount of each compoundin the product mixture relative to the internal standard of knownconcentration. It is possible that at the milder reaction conditionsthat heptadecane (C₁₇) is underestimated as described in the previoussection. Although it might not be completely accurate, the data shouldstill provide, at worst, a conservative estimate of yield. FIGS. 27 and28 show the percentage of C₈-C₂₀ alkanes and alkenes respectively,formed at different temperatures and times. It is important to note thatthe alkene that was quantified was the alkene peak that directlypreceded the alkane peak. As explained earlier, data from GC/MS suggestthat is likely a 1-alkene, however this has not been confirmed by othermethods. Data from the GC/MS also suggest that the small peaks followingthe alkane (another “ladder”) is also an alkene with the double bond ina different position. When the data was first analyzed, these peaks werediluted out. The GC vials were diluted prior to analysis because the C₁₇peak overloaded the GC when a more concentrated sample was analyzed.FIGS. 20-26 represent analysis from the more concentrated samples (i.e.all reaction product dissolved in 10 ml of pentane); however, peakintegrations were conducted using the diluted samples. Because themethod used to quantitate the compounds is relative to the internalstandard that was added during extraction of the products from thereactor, it should not affect the result. As such, the small alkene peakthat appears after the alkane in the chromatogram is not considered inthis analysis but will be discussed briefly later. The data representsthe averages of duplicate runs and the error bars represent the standarderror between the two runs. Looking at the FIGS. 27 and 28, it is clearthat more alkanes are formed compared to alkenes. As well, the errorbars at the more severe reaction conditions are smaller than at themilder conditions as has been observed in other results.

At 350, 370, 390, and 410° C., the amount of alkanes and alkenes formedincreases with time. At 430° C. and above, the amount of alkanes andalkenes in the C₈-C₂₀ range start to decrease as the reaction time isincreased. For example, at 430° C. a 4-hour reaction results in acombined total of 25.2% C₈-C₂₀ alkanes and alkenes while after 8 hrs ofreaction, this values decreases to 10.7%. At 450° C., and reactionslonger than 4 hours, and 500° C. relatively little product in the C₈-C₂₀range is formed. The maximum amounts of C₈-C₂₀ alkane and alkenes areformed at 410° C. after 4 hr (32.7%) and 8 hr (32.1%) reactions and at390° C. after 8 hrs (32.9%).

Cracking Patterns of C₈-c₁₇ Hydrocarbons

The data from the chromatograms provides a decent estimation of yieldsbut it can also be used to study the cracking behavior. Both molarselectivity and alkane to alkene ratio can give a good understanding ofcracking behavior. This section will focus on the molar yields of thealkanes while the next section will look at the molar ratio. Peak areasfrom GC integration were converted into molar yields for C₈-C₂₀ alkanes.This data is presented in FIGS. 29-32. The figures represent the averageof duplicate runs and the error bars represent the standard errorbetween these runs. For clarity, the lower temperatures (350-390° C.)are illustrated with open data point markers and dashed lines while thehigher temperatures (430-500° C.) are illustrated with solid data pointmarkers and solid lines. The middle temperature, 410° C. is illustratedwith x's and a longer dashed line (see legend). The cracking pattern ofalkanes is of important because alkanes are the primary products ofinterest. The cracking behavior of alkenes is also important and isaddressed in the next section on molar ratios between alkanes andalkenes.

In FIGS. 29-32, similar trends occur at each reaction time of 0.5, 1, 4,and 8 hours, however they occur at different temperatures. At themildest conditions (low temperature, low time), very little reactionproduct is formed. For example at 350° C., products do not start forminguntil 4 hours.

Alkane:Alkene Ratio

The data from this experiment can be used to analyze the molar ratio ofalkanes to alkenes, an important parameter in hydrocarbon cracking. Peakareas were used to calculate the alkane:alkene ratio. FIGS. 33-36 showthe molar ratios of alkanes to alkenes as a function of carbon numberand time at different reaction temperatures. Chains with 17 carbons(heptadecane/heptadecene ratio) were excluded from these figures becausethe ratio was so large that it made it difficult to see the changes inC₈-C₁₆ ratios. This ratio is discussed separately in the next section.As in the previous section, the figures represent the averages fromduplicate runs and the error bars represent the standard error betweenthe runs. Errors were generally smaller for this data than for theestimations of yield. It is likely that a large percentage of the errorbetween the two samples is due to the extraction method and the amountof compound that is extracted. This would likely affect the amount ofcompound in the extracts, but unlikely to affect the ratio of alkanes toalkenes, which should be independent of concentration.

It is important to note that because this data represents the average ofonly duplicate runs significance tests cannot be conducted. Generaltrends will be noted based on the graphs but it is not known whether ornot any of the differences mentioned have true statistical merit. Forthis set of experiments, the molar ratios are almost always greater than1, meaning that more alkanes are produced than alkenes. Looking back atthe results of the initial studies (FIG. 11), it is clear that duringthe five-minute reactions at 500° C., the alkenes were produced ingreater quantities than the alkanes. This is also evident for the0.5-hour reactions at 450° C., but to a lesser extent. The results ofthe current experiment show that the molar ratio is less than one atonly a few conditions, most noticeably at 450° C. for the 4 and 8 hourreactions and only for certain carbon numbers, namely C₁₂-C₁₄ and C₁₆.

Changes in Molar ratio Over Time

In FIGS. 30-33, the trend is that at 390° C. and 410° C., the molarratio increases with time. A higher molar ratio indicates that morealkanes are produced relative to alkenes, or alkanes are producedpreferentially to alkenes. For example, at 390° C. the molar ratio of C₈increases from 1.69±0.07 after 0.5 hours to 5.55±0.09 after 8 hours.Likewise, the molar ratio of C₁₆ increases from 0.69 0.11±after 0.5hours to 4.17±0.22 after 8 hours. Similar trends are observed for thecarbon numbers in between. At 430° C., some compounds (C₈, C₁₀, C₁₁, andC₁₅) show increasing molar ratio with time, however others (C₉, C₁₂,C₁₄, C₁₆) show a decrease in molar ratio between the 4 and 8 hrreactions. At 450° C., it looks as if the molar ratio begins to decreaseeven earlier, between the 1 and 4 hr reaction. In summary, the molarratio increases with time from 0.5-8 hrs until a certain temperaturewhere the longer reaction times result in a decrease in molar ratio.

Changes in Molar Ratio with Temperature

The temperature does not have as much of an influence on the molar ratioas time does at temperatures between 390° C. and 430° C. At eachreaction time there appears to be a maximum ratio at a certaintemperature and as the reaction time is increased the temperature atwhich the maximum occurs decreases. For example, for 0.5 minutereactions, the maximum ratios appear to be at 410° C. or 430° C. whilefor 8 hr reactions, the maximum ratios occur at much lower temperaturesaround 370° C. or 390° C.

Time and Temperature Effects

Although statistical analysis was not conducted, it is clear that bothtemperature and time affect the molar ratio. The mildest conditions (lowtemperatures and times) results in a relatively low molar ratio but sodo the most severe (longest times and highest temperatures). The optimalratio lies somewhere in between these two extremes. At the conditionstested, the largest ratio occurred at 370° C. for 8 hr reactions. The 8hr reaction at 350° C. did result in slightly lower ratios, howeversince reactions were not conducted at times longer than 8 hrs, it ispossible that reactions longer than this at 350 or 370° C. could resultin higher molar ratios.

Changes in Molar Ratio with Carbon Number

Another variable to consider is the number of carbons that the alkaneand alkene chains have. For this analysis, C₈-C₁₆ carbons wereinvestigated. The distributions of molar ratios for each compoundrelative to one another appears to be consistent at the different timesand temperatures aside from the fact that at higher temperatures (430°C. and above) the molar ratios of C₈ and C₉ decrease more, relative tothe other compounds. For most of the temperatures, C₈-C₁₁ and C₁₅ havelarger molar ratios than C₁₂-C₁₄, and C₁₆. It is evident that C₁₅ hasthe highest molar ratio, while C₁₆ has the lowest. For example at 410°C. a 1 hr reaction results in a molar ratio of 4.75±0.06 for C₁₅ butonly 1.20±1.16 for C₁₆. At 390° C. an 8 hr reaction results in a molarratio of 8.86±0.07 for C₁₅ and 4.17±0.02 for C₁₆.

Molar Ratios of C₁₇

FIG. 37 shows the molar ratio for C₁₇, or heptadecane to heptadecene. Ithas been established that heptadecane is the major reaction product andthat there is very little heptadecene. The molar ratios, which aresubstantially higher for C₁₇ than for C₈-C₁₆, reflect this. In theC₈-C₁₆ range, C₁₅ had the highest molar ratios. At 390° C. the molarratio after an 8-hour reaction was 8.86±0.07. In contrast, at the samecondition the molar ratio for C₁₇ was 39.0±0.71. Again, becausereactions longer than 8 hours were not conducted, it is possible thatthe maximum molar ratio lies outside the conditions tested. The largestmolar ratio for C₁₇, 43.53±3.59, occurred at 410° C. for an 8 hrreaction. The data suggests C17 follows the same trends as the C₈-C₁₆hydrocarbons. For example at 390-430° C., the molar ratio increases withtime, but at higher temperatures such as 450° C., longer times (4 and 8hours) result in decreased ratios. At 500° C., the ratios are low forall of the times tested.

Analysis of Light Ends (Gas Fraction)

Composition

Typical chromatograms showing the composition of the gas fraction asanalyzed on GC-TCD are presented in FIG. 38. Methane (CH₄), carbondioxide (CO₂), and room air standards were also analyzed and are shownin FIG. 39. Due to the sensitivity of the detector, N₂ and O₂ aredetected as single peak. This means that the first peak in thechromatograms can be N₂, O₂, air or any combination of the three. Forsimplicity, this will be referred to as the “N₂/O₂ peak”. Comparing peakretention times from the sample (FIG. 37) with the peak retention timesfrom the standards (FIG. 38) it is evident the gaseous fractions contain“N₂/O₂”, CH₄, and CO₂. The majority of the N₂/O₂peak can likely beattributed to the N₂ atmosphere inside the reactor and small amounts ofair from the sample vacutainer or the injection syringe.

There are small amounts of air present in the CO₂ and CH₄ standards(FIG. 39), indicating that small amounts of air are entering the GC,likely through the syringe. There are also two sets of smaller peaks atlater retention times, which appear to be in doublets. These peaks arelikely light hydrocarbon gases such as ethane and propane, however thiswas not confirmed analytically. Analysis of the gaseous fraction wasanalyzed numerous times and compositions obtained from the fractionsafter one hour reactions at 390° C. and 410° C. as well as a 30 minutereaction at 500° C. all yielded similar results.

Percentage of Feed

FIG. 40 shows the percentage of gas formed at various temperaturesduring 1 hr reactions. For this experiment, reactions were conductedusing approximately 5.0 g of stearic acid feed instead of the usual 1.0g. More starting feed was used so that the difference in the weight ofthe gas, measured by weighing the reactor before and after venting, wasdetectable on the scales available in the lab. FIG. 40 shows that as thetemperature increases, the amount of gas products formed also increases.to At 370° C., only 0.50 wt. % of gas is formed but at 430° C., anaverage of 7.89 wt.% of gas product is formed. Reactions were conductedat 450° C.; however, with that much feed the pressure build-up was sohigh that two of the reactors leaked and two of the reactors spewed oilduring venting despite the fact that the samples were allowed to coolovernight and the vent valve was turned slowly. Because this resulted ina loss of oil, no accurate data was obtained. The shape of this graphindicated that in the temperature range tested, the formation of gas isnot linear with respect to temperature.

Estimate of Liquid Yield

To get a crude estimate of liquid yield, the liquid product wasextracted with a Pasteur pipette from the reactor (no solvent was added)and weighed. Results are presented in FIG. 41. At 390 ° C., there was noliquid product in the reactor. The product consisted of white-brownpowder. At 410° C., after a one-hour reaction, three runs (data notshown) also resulted in no liquid product, however the other 3 runsresulted in liquid products between 58-71%.

Extent of Reaction

Generally, fatty acids do not create sharp peaks on the GC. They have atendency to spread on the column resulting in wide, “shark fin” peaksthat are difficult to quantify. For this reason, fatty acids are firstderivatized into methyl esters before GC analysis. To avoid changing thestructure of the other sample products, none of the samples werederivatized prior to analysis. Therefore, quantitation of unreacted feedbased on the underivatized samples is not likely to be accurate.Furthermore, pentane was used as the primary extraction solvent, whichis not the best choice for dissolving fatty acids. The stearic acid peakis not likely to be totally representative of the actual amount ofunreacted material. FIG. 42 shows the percentage of stearic acid feedconverted into product during the reactions (i.e. 100% of unreactedstearic acid). The data represents the average of fours runs. Asexpected, as the temperature increases, more feed is converted. At thelowest temperature, 350° C., only 31.70% of the stearic acid isconverted. At the highest temperature, 450° C., nearly 95% of theproduct was converted. It is also worthwhile to note that at the highertemperatures, the error bars were much smaller than at the lowertemperatures. This is likely due to the nature of the reaction productas well as the extraction method. At lower temperatures where theproduct is mostly solid, it sticks to the reactor and is difficult toextract. Despite stirring this material during the extractions, it ismore likely that some of the compound may not have been dissolved in thepentane. At higher temperatures, when the reaction products are liquid,they dissolve easily into the pentane.

Minimum Cracking Temperature

To determine the minimum temperature at which decarboxylation occurs,4-hour reactions were conducted starting at 350° C. and decreasingtherefrom. Duplicate runs at 255° C. still showed a C₁₇ peak (FIG. 43).Analysis of a gas sample taken from this reaction showed an extremelysmall, but evident CO₂ peak as shown in FIG. 44.

Pyrolysis of Oleic Acids

It is of interest to see if the cracking behavior of an unsaturatedfatty acid differs from that of a saturated fatty acid. Oleic acid, afree fatty acid with cis-double bond in the 9-position, was pyrolyzedfor one hour at 410° C. using standard reaction and extractionprocedures. The GC-FID chromatogram is shown in FIG. 45. The mainproducts were identified using the GC-FID chromatograms and comparingthem to the external alkane and fatty acid mixtures as well as GC/MS.The amounts of various compounds were determined semi-quantitatively andare presented in FIG. 46. This graph shows the averages of the foursruns and the error bars represent standard error. FIG. 46 shows theprimary reaction products resulting from the thermal cracking of oleicacid at 410° C. after 1 hr. The largest amount of product formed was8-heptadecene. Two bars show 8-heptadecene, possible due to a differencein conformation. This indicates that decarboxylation is likely aninitial step in the thermal cracking of oleic acid. The most notabledifference between oleic acid and stearic acid cracking is the absenceof the prominent alkane/alkene ladder series at higher carbon numbers.This ladder is evident at lower carbon numbers, C₉ and lower and FIG. 46shows that heptane/heptene, octane/octane, and nonane/nonene were amongthe primary reaction products formed. This would be consistent withcracking at the double bond of the decarboxylated chain. It is alsointeresting to note the presence of nonanoic and decanoic acid, atconcentrations of 11.31±0.52 and to 18.41±1.01 mg/g feed, respectively.

The sum of the products identified in FIG. 46 only represents 18.4% ofthe total products formed (including the gas products). Looking at thechromatogram (FIG. 45), it is evident that there are a number of minorpeaks. Analysis of these peaks by GC/MS indicated that several of thepeaks are likely cyclic components such as cyclopentanes andcyclohexanes with different methyl and ethyl groups attached.

Gas samples were also collected from the pyrolysis of oleic acid.Duplicate chromatograms from the GC-TCD analysis are shown in FIG. 47.Results are similar to the gas products formed during pyrolysis of oleicacid. The results show a large N₂/O₂ peak, a small CH₄ (methane) peak aswell as a CO₂ (carbon dioxide) peak.

VI. Hydrolysis and Pyrolysis of Neat Oils and Fats Hydrolysate Analysis

TLC-FID Analysis

FIGS. 48-52 show select chromatograms from the TLC-FID analysis of thehydrolysate fractions. FIG. 49 shows the chromatogram for the bleachedfancy hydrolysates and FIG. 48 shows the chromatogram for the canola oilhydrolysates. It is clear that a single peak results likely indicatingthat only one type or class of lipid is present. Duplicate chromatograms(not shown) showed the same results. Because the conditions were severeand a single peak is evident, it is very likely that all of the TAG'sare converted to FFAs. To confirm this, the retention times of differenttypes of lipids were determined by analyzing a standard mixture of oleicacid TAG, DAG, MAG, and FFAs using the same method. These results arepresented in FIG. 50. The chromarod analysis is such that the FIDdetector will scan down the rod. This means that the first peak toappear on the chromatogram (lowest scan time) will be the one thattravels furthest up the rod during the TLC. In this case, the TAGfraction should appear first followed by the FFAs, DAGs and then MAGs.This is labeled on the standard curve and has been verified severaltimes in other studies. The DAG and

MAG peaks are clear, however, there is not great separation between theTAG and FFA peaks. It is evident that there are two separate peaks andthat the TAG peak is larger than the FFA peak. The same trend has beenshown in duplicate samples. Comparing the single peak from the samplesand the standard, it is clear that the to single peak aligns with theTAG and FFA peaks, however, because of the poor separation, it can notbe stated conclusively that the samples contain nearly 100% FFA.

Because the results indicate that there are no intermediate DAG or MAG,the only other possibility is that the peak represents unreactedtriglycerides. To confirm that the single peak does indeed representFFA, samples were plotted on the chromarods and then spiked withstandard. FIGS. 51 and 52 show that the when the sample is spiked withstandard, the height of the FFA peak increases relative to the height ofthe triglyceride peak. In FIG. 51, equal volumes of sample and standardare plotted on the chromarods. Again there is not good separation,however, it does look like there are two peaks and that the second oneis so large that it almost completely overlaps the first. This wouldindicate that the single peak from the sample is adding itself to thesecond FFA peak of the standard. FIG. 52 shows standard plotted with thestandard with a ratio of 2:1 by volume standard/sample. In this case,there is better separation between the TAG and FFA peaks and the peaksappear to be nearly equal in size. Comparing this to the standardchromatogram, where the TAG peak is clearly larger than the FFA peak, itis evident that the single peak is adding itself to the second FFA peakfrom the standard. This indicates that the canola oil and bleached fancyhydrolysates are composed almost completely of FFA. It is assumed thatthe hydrolysates of the poultry tallow and the yellow grease are alsocomposed predominantly of FFA. Although no lipid analysis was run onthese hydrolysates, analysis of the pyrolysis fractions of all four oilsand fats appeared similar.

GC-FID Analysis

Initially, hydrolysates from poultry tallow were pyrolyzed for fourhours at 410° C. as per normal procedures. The extracts were thenanalyzed on GC-FID. The chromatograms are presented in FIGS. 53 and 54.Canola oil, and two grades of beef tallow (Bleached Fancy (BF) andYellow Grease (YG), were pyrolyzed at 410° C., but for one hour (FIG.55). Bleached fancy hydrolysates were also pyrolyzed at 390° C. for onehour. The chromatograms from these reactions are presented in FIGS. 55and 56. Note that the samples were prepared at different concentrations.Looking at the figures, the alkane/alkane ladder is prominent.

The chromatograms show that there are numerous compounds in betweenthese ladders. The chromatograms of the neat oils and fats are not asclean as the chromatograms from the stearic acid pyrolysis. Numerousanalyses of hydrolysates indicate the feedstock contains mainly freefatty acids. There was no evidence that there were large amounts ofcontaminants that may result in peaks shown in FIG. 56. To verify this,hydrolysates were dissolved in pentane and run on GC-FID (FIG. 57). Amassive peak around at a retention time resulted. Due the spreadingalong the baseline, it is likely that this peak is composed of a mixtureof fatty acids. No other peaks were evident. To see if any of thecompounds in the pyrolysis products were water-soluble contaminants, asimple water extraction was conducted on the pyrolytic oil. Afterwashing with water, the organic sample was separated and re-analyzed onGC-FID (FIG. 57). The figures are very similar, indicating that thewater extraction had little effect on the extraction products. Thesesimple experiments show that the peaks are organic in nature and arelikely the result of the pyrolysis reaction. It is possible that thepeaks are unreacted feed or lower carbon number free fatty acids. Sincethese have a tendency to spread on the baseline they are difficult toseparate and result in poor baseline. Secondly, the results of the oleicacid analysis show that pyrolysis of unsaturated free fatty acids mayresult in the formation of numerous cyclic compounds.

GC/MS Analysis After Derivatization with Diazomethane

As previously mentioned underivatized fatty acids do not result in cleansharp peaks on the GC column and conditions that were utilized in thiswork for the analysis of the hydrocarbon product and because they spreadon the column they may overlap other compounds. Products were notroutinely derivatized because of the potential risk of changing theproduct distribution during the derivatization process and also becausethe stearic acid feed resulted in relatively clean chromatograms wherethe fatty acids and hydrocarbons were clearly separated. The advantageto derivatizing these products would be to get a more accurateestimation of the fatty acid content. To estimate the unreacted feedthis approach was taken as described previously, however in these casesthe hydrocarbons were considered for analysis. Because the pyrolysisproducts from neat fats and oils contained many unidentified compounds,it was of interest to analyze them on GC/MS. In an attempt to purify thesample and to eliminate any fatty acid spreading along the baseline,bleached fancy pyrolytic oil was first derivatized with diazomethane(without drying) and analyzed by GC/MS. An underivatized sample was alsorun to determine any effects of running the derivatized samples withoutthe drying steps. These chromatograms are presented in FIG. 58-60.

Throughout this application, various publications are referenced. Thedisclosures of these publications in their entireties are herebyincorporated by reference into this application in order to more fullydescribe the compounds, compositions and methods described herein.

Various modifications and variations can be made to the materials,methods, and articles described herein. Other aspects of the materials,methods, and articles described herein will be apparent fromconsideration of the specification and practice of the materials,methods, and articles disclosed herein. It is intended that thespecification and examples be considered as exemplary.

TABLE 1 List of chemicals used in study. Name Catalogue NumberManufacturer Supplier Pentane P399-4 Fisher Chemicals Fisher Scientific(HPLC Grade) (Fair Lawn, NJ) Toluene T290-4 Fisher Chemicals FisherScientific (HPLC Grade) (Fair Lawn, NJ) Nonadecanoic Methyl N5377 SigmaSigma-Aldrich Co. Ester St. Louis, MO (min 98%, GC) Alkane Standard04070 Fluka Sigma-Aldrich Co. Solution C₈-C₂₀ St. Louis, MO CarboxilicAcid N/A Sigma Sigma-Aldrich Co. Standard (GC) Solution St. Louis, MOAlumina, desiccant A-2935 Sigma Sigma-Aldrich Co. Grade H-152 St. Louis,MO Nitrogen, Compressed N/A Praxair Praxair, Edmonton, AB P.P. 4.8Chlororform, HPLC C606-4 Fisher Chemicals Fisher Scientific Grade (FairLawn, NJ) Hexanes, HPLC Grade H302-4 Fisher Chemicals Fisher Scientific(Fair Lawn, NJ) Acetic Acid, glacial, A-0808 Sigma Sigma-Aldrich Co. ACSReagent Grade St. Louis, MO TLC Standard, 25% — Nu-Chek Prep Inc.Elysian, MN (w/w) of each of oleic acid, monoolein, diolein and trioleinDiethyl ether Fisher Chemicals Fisher Scientific (Fair Lawn, NJ)

TABLE 2 Fatty acid composition of the feed fats and oil Fatty Acid (%)Feed Material C14:0 C16:0 C16:1 cis C17:0 C18:0 C18:1 trans C18:1 cisC18:2 C20:0 C18:3 C22:0 Bleached Fancy 2.56 24.98 3.13 1.05 16.52 2.6137.82 5.87 0.18 0.61 — Yellow Grease 1.14 15.39 2.45 0.36 7.45 4.4346.19 15.48 0.30 2.26 0.18 Canola Oil 0.07 5.10 0.29 0.06 2.21 — 63.6317.33 0.62 6.91 0.30 Poultry Tallow 0.76 22.54 7.25 0.14 5.67 0.68 43.9214.66 0.10 1.16 0.03

TABLE 3 Percentage of saturated and unsaturated fatty acid in feed fatsand oil Saturates Monounsaturates Polyunsaturates Feed Material (%) (%)(%) Bleached Fancy 46.22 44.76 7.24 Yellow Grease 25.37 54.18 18.43Canola Oil 8.62 65.55 24.57 Poultry Tallow 29.62 52.55 16.95

TABLE 4 Sand bath specifications Techne SBS-4 Sand Bath SpecificationsOverall Size (Diameter × Height), in 13.2 × 18.2 Working Volume(Diameter × Height), in 7.0 × 5.5 Temperature, ° C.  50-600 TemperatureStability @ 50° C. with TC-8D ±0.3° C. Air Pressure, PSI 3 Air Flow CFM3 Weight of Media, lbs 19.8

TABLE 5 Groups methylated by different derivatization compoundsDerivitization Compound Types of compounds methylated Boron TrifluorideTAG, DAG, MAG, FFA Diazomethane FFA Sodium methoxide TAG, DAG, MAG, FFAMethanolic HCL TAG, DAG, MAG

TABLE 6 Experimental conditions for preliminary pyrolysis reactions. X'sindicate reactions were conducted at the specified conditions. TimeTemperature (° C.) (min) 350 400 450 500 550 30 XX XX XX XX — 5 — XX XXXX XX

TABLE 7 Experimental Conditions for the pyrolysis of stearic acid.Temperature (° C.) Time (hr) 350 370 390 410 430 450 500 0.5 — — XX XXXX XX XX 1 — XX XX XX XX XX XX 4 XX XX XX XX XX XX XX 8 XX XX XX XX XXXX — X's indicate reactions conducted.

1. A method for producing a fuel or solvent from a fatty acid resource,comprising: a. separating one or more fatty acids from the fatty acidresource; and b. converting the fatty acid to one or more alkanes oralkenes.
 2. The method of claim 1, wherein the fatty acid resourcecomprises vegetable oil, animal fats, spent cooking oil, lipids,phospholipids, or triglycerides.
 3. The method of claim 2, wherein thevegetable oil comprises corn oil, cottonseed oil, canola oil, rapeseedoil, olive oil, palm oil, peanut oil, ground nut oil, safflower oil,sesame oil, soybean oil, sunflower oil, algae oil, almond oil, apricotoil, argan oil, avocado oil, ben oil, cashew oil, castor oil, grape seedoil, hazelnut oil, hemp seed oil, linseed oil, mustard oil neem oil,palm kernel oil, pumpkin seed oil, rice bran oil, or walnut oil, acombination thereof.
 4. The method of claim 2, wherein the animal fatcomprises blubber, cod liver oil, ghee, lard, tallow, a derivativethereof, or a combination thereof.
 5. The method of claim 1, wherein thestep (a) comprises (i) separating one or more triglycerides from thevegetable oil or animal fat, and (ii) hydrolyzing the triglyceride toproduce the free fatty acid, and (iii) isolating the free fatty acid. 6.The method of claim 1, wherein the fatty acid comprises a saturatedfatty acid, an unsaturated fatty acid, or a combination thereof.
 7. Themethod of claim 1, wherein the fatty acid comprises butyric acid, lauricacid, myristic acid, palmitic acid, stearic acid, arachidic acid,alpha-linolenic acid, docosahexaenoic acid, eicosapentaenoic acid,linoleic acid, arachidonic acid, oleic acid, erucic acid, a naturallyderived fatty acid from a plant or animal source, or a combinationthereof.
 8. The method of claim 1, wherein prior to step (a), the fattyacid resource is further purified by by extraction or distillation. 9.The method of claim 1, wherein step (b) comprises heating the fatty acidto convert all or substantially all of the fatty acid to an alkane, analkene, or a mixture thereof.
 10. The method of claim 9, wherein theheating step is conducted at a temperature from 220° C. to 650° C., at apressure from ambient to 2,000 psi, for a duration of two seconds up to12 hours.
 11. The method of claim 9, wherein the heating step isconducted at a temperature from 250° C. to 500° C. for two seconds up to8 hours.
 12. The method of claim 9, wherein the heating step isconducted in the presence of a decarboxylation catalyst.
 13. The methodof claim 12, wherein the decarboxylation catalyst comprises activatedalumina.
 14. The method of claim 9, wherein the heating step (b) isconducted under an inert atmosphere.
 15. The method of claim 14, whereinthe inert atmosphere comprises nitrogen.
 16. The method of claim 1,wherein the steps (a) and/or (b) are continuous.
 17. A fuel or solventproduced by the method of claim 1, wherein the fuel or solvent issubstantially free of aromatic compounds.